a)=
7x(8+2x[4+3x(14-8)-20]=
7x(8+2x[4+3x7-20])=
7x(8+2x[4+21-20])=
7x(8+2x5)=
7x18=126
b)=
(180-15)+5x(24-5x[19-2x(17-8))=
165+5x(24-5x(19-2x9))=
165+5x(24-5x1)=
165+5x19=
165+95=260
c)=
5+2x(3+2(5+5x4))=
5+2x(3+2x25)=
5+2x53=
5+106=111
d)=
[50-3x(99-84)]x(2+4x[8+5x(3+21])=
[50-3x15]x(2+4x[8+5x24])=
5x(2+4x128)=
5x(2+512)=
5x514=2570
e)=
7x(11+2x[72+8)-11]+31=
7x(11+2x80-11]+31=
7x(11+160-11)+31=
7x160+31=1151
f)=
([63-17+16]x2-123)+[55-15x3]x2=
(62x2-123)+(55-45)x2=
(124-123)+10x2=
1+20=21